CLEVELAND, Ohio - Serial rapist Nathan Ford, who argued he had no memory of many of the 15 rapes linked to him by DNA found in rape kits, was found guilty Friday of three counts of rape and three counts of kidnapping by a Cuyahoga County jury after a nearly two week trial.

Ford, 49, still faces charges in three other rape cases.

He already is serving more than a century in prison for previous rape convictions involving eight women.

Ford will be sentenced May 2.

The current case involved rapes reported by women between 1995 and 2000. Two of the victims testified about the attacks during the trial.

Charges involving a fourth victim were dismissed.

Ford grabbed several of the victims off the street, threatening them with a gun or using choke holds to force them to submit, prosecutors said.

Contrary to his claims of memory loss, they say his behavior during the rapes was planned, organized and calculated.

Ford, a former Lake County probation officer, often beat his victims or threatened to shoot or strangle them, and in some cases wore gloves or made victims wash to remove evidence of his crimes, according to motions filed by assistant county prosecutors Mary Weston and Daniel Van.

Two doctors in 2006 said Ford likely had a form of frontotemporal dementia, based on scans of this brain and other tests. "It is virtually certain that his violent criminal behavior is a result of the disease," one wrote in a report.

However, the same doctor said that didn't necessarily mean Ford met a legal definition for "insanity." To prove that, a person must prove their disease or mental health issues prevented them understanding what they did was wrong.

Cuyahoga County Common Pleas Judge Pamela Barker in December denied Ford's motion to change his plea to not guilty by reason of insanity. "An irresistible impulse cannot excuse the actions of a person who does not otherwise meet the legal definition of insanity," her journal entry stated.

Cases first linked by DNA

Ford first appeared on law enforcement's radar about a decade ago. Cleveland police were working to solve several cases that a detective had a hunch were the work of a serial rapist. A state pilot project was also paying paid police departments to send rape kits for testing.

The forensic testing linked the rapes of eight women between 1996 and 2004 to a single man. An anonymous tip eventually helped detectives connect Ford to the cases.

In 2006, Ford agreed to plead no contest to more than 50 charges of rape. He later, after the brain scans were complete, tried to take back the pleas but the judge, and later appeals courts refused his request.

Five years ago, Cleveland police agreed to send more of their stored rape kits for testing. This time there wasn't a grant program. It was a decision made by Michael McGrath, who was police chief at the time and now serves as the city's public safety director.

Detectives located nearly 5,000 kits dating back to 1993 that hadn't been tested for DNA. The effort has lead to the indictments of hundreds of men, many accused in multiple rapes.

Ford still was sitting in prison. As the kits were tested, his DNA popped up in several of them.

Investigators and prosecutors from the Sexual Assault Kit Task Force are looking into several case Ford may be linked to in Northeast Ohio.

Ford's targets, records show, included people from all walks of life: Drug addicts, prostitutes, a college student, schoolteacher and three teenagers, one of whom had a prosthetic leg.

In Cleveland, his rapes occurred on both the East and West sides of town, often in the same areas, according to prosecutors.

Several victims were snatched off the street and dragged to secluded areas. One was a home invasion and another was studying in a Cleveland State classroom.

"I will kill you, I've killed people before," he told one victim, according to her report.